This invention relates to a cylinder lock and particularly to a cylinder lock in which pin-tumblers which are urged by springs in one direction are arranged such that the axes thereof lie in different parallel planes normal to a diametrical plane of a rotary cylinder.
Cylinder locks with pin-tumblers are known in the art. In order to improve the security of cylinder locks, improvements have been made in the constructions thereof so as to make the locks difficult to pick. U.S. Pat. No. 4,142,389 discloses a cylinder lock in which each tumbler of the housing of the lock is made of two parts, one part telescopically slidable within the other, both parts being urged by springs against a corresponding tumbler received in the rotating cylinder which corresponding tumbler is likewise made of two telescopic parts. The key to operate the lock has concentric projections or recesses on a planar face of the key. Such a lock increases the positions, permutations, and combinations of the pin-tumblers so that the lock will be more difficult to pick than other known locks which do not comprise telescopic pin-tumblers. However, the above-mentioned lock still can be picked if one uses more time than is necessary to pick those with non-telescopic pin-tumblers, since the axes of the telescopic pin-tumblers are aligned on a single longitudinal plane of the cylinder as in other known cylinder locks.